To establish an analytical method for phenolic compounds in foodstuffs and tissue samples, we determined five simple polyphenols, five tea polyphenols and five isoflavones using high performance liquid chromatography equipped with a coulometric array detector. When simple polyphenols were detected with eight coulometric array detectors at 350 to 700 mV, trihydroxyphenols gave the highest signal at 350 mV, o- and p-diphenols at 400 mV, and m-diphenol at 700 mV. In tea polyphenols with m-diphenolic A ring and di- or triphenolic B ring, strong signals were detected at 400 and 700 mV. In isoflavone aglycons having monophenolic or m-diphenolic A ring, monophenolic B ring, and C ring with 4-carbonyl group, a strong signal was observed at 500 or 550 mV and at 700 mV. However, equol without 4-carbonyl group gave a single peak at 650 mV. These results suggest that the signal at 350-400 mV is due to the conjugated OH groups present in o- or p-derivative, the signal at 500-550 mV is due to the 4-carbonyl group and the signal at 700 mV to isolated OH groups present in monophenols or m-diphenols.
All Science Journal Classification (ASJC) codes
- Food Science
- Chemical Engineering(all)
- Industrial and Manufacturing Engineering